Arm resonance

[laatsch55]

The above post of mine proves how physics has impact on sound reproduction. Even hydrostatic gets involved!!!




Truly sorry for the off topic!

@borchee mate thanks for the conversation. I don't disagree with you, I just stand on details.

MM, don't EVER be sorry for off-topic here..

 

[vince666]

We see eye to eye. My goal in a debate is for me to learn something - I'm right until I'm proven wrong, which I can happily accept.

my hat off on you for this , Borut.

and regarding the debate, still only read too quickly and it's late here, then my brain is half-sleeping. (will read it again more carefully tomorrow, after having my coffee)

i liked what Makymak (and you as well) described about the effect of the air which is still a fluid, so the volume still has some importance like when you have, in the water, two bodies of the same weight but evidently different volume.
But, to me, this looks more like the way of thinking of a pure physicist while, often, the engineer tries to find a "simplier" solution by also (purposedly) ignoring what might provide a negligible effect... and i guess that, being in gas state and not liquid state, the fluid surrounding the body has a lot less effect on it, especially if it's not even moving so that you can also avoid considering the fluid-dynamics otherwise involved.
So, a few negligible effects from an "engineer" point of view but indeed such things are still there and have importance from "pure physicist" point of view.

Anyways, if there is a lot of humidity in the air then this effect might be a bit less negligible. (just to add another variable in the mix)

Then.... i saw a bunch of brain-squeezing around this question of yours, Borut, and which isn't a so easy one to answer... or, ar least, it needs that you think about it with care... then, nice one!

But, unless i missed the answer on some previous post here above, nobody still answered my question: "what weights more, half chicken dead or half chicken alive?"

 

[vince666]

Vince, my point is that laws of physics seem to have no place in HiFi. Just look with what a TT newbie asking about a turntable set-up is usually tortured with. This area is so full of variables and unknowns, that anyone stating he's got his TT set up perfectly is dillusional. Example: The consensus about setting the anti-skate force is that there is no consensus. I'm working towards your thesis.

absolutely so!

and maybe VTF is the easiest thing to get right, by simply using some kind of scale.
All the rest can be really messy... so, TT setup is OK until you can stay within acceptable ranges... it's the art of compromise... otherwise, to calculate things just exactly is an impossible mission.... way too many variables, including the different shapes of the grooves of records to play since they contain different songs.

 

[Bob Boyer]

...

But, unless i missed the answer on some previous post here above, nobody still answered my question: "what weights more, half chicken dead or half chicken alive?"

I dunno, but can I smoke that dead chicken half and put some Alabama white sauce on it? And while we're at it, howthehell you got one half of a chicken live anyway? Seems to me, by definition, one half a chicken be a dead chicken. Either way.



But seriously, like others, I'm enjoying the hell out of this conversation, even as I check my SME 309's tracking force with a plastic balance beam and plastic discs of various weights that came with my first AR XA turntable.



1.25 grams, exactly.

 

[vince666]

howthehell you got one half of a chicken live anyway?

That's the right answer!

But, hey, it happens more times especially if you ask my above question by person and someone has to answer immediately that they say any of the two halves weights more...
So i can reply: "but have you ever seen half chicken alive?“
It's more a joke than a real question but, hey, many don't get it quickly.
Of course, here, being a written question, you'll never fail to get it properly.


your scale there isn't too different than what i use here.
i own a Shure sfg-2 which is another oldschool one which works by balancing as well... but it has a slider to set the weight.

 

[marcok]

Hi Marco. The Elliptic filter is not a subsonic filter, nor is it a traditional hi-pass filter (text from the designer):

" Phono Warp first order "elliptic" filter with vertical (L-R) rejection of c. 3dB at 140Hz and c. 36dB at 2Hz. Nominally 0dB rejection of horizontal (L+R) rejection. "

It is only active on vertical input (L-R) and not on horizontal (L+R), so it literally removes "warp" signal (record pushing cartridge up) without effecting recorded musical information, even if it's very low frequency. Above 150Hz it is essentially non-existent as well, but it really doesn't matter- it is completely inaudible. It's an excellent design and I am looking into have a stand-alone right now. It won't be before Christmas, but soon...

Completely by-passable as well but I could have hard-wired it into my preamp. You don't know it's working!

Thank you ,
now I must study .
Ciao
Marco

 

[marcok]

Jim , before going on
what do you mean for elliptic filter ?
For me it's a Cauer filter .
https://en.wikipedia.org/wiki/Elliptic_filter
If I have understood well ,
you mean a device that filters only L-R part
( in other words below 150 Hz the signal is mono )
Good idea ! Below 150 Hz stereo mode is useless .
Carver ( I think ) uses a subsonic filter with auto correlator to
obtain the same result .

Ciao
Marco

 

[J!m]

As I understand it, it is best described as a balanced line rejecting common mode noise. The + and - signals present on both channels cancel each other out. It is called elliptic, because the shape of the response is elliptical. (and I'm not a fan of "warp filter")...

There was one empirical example by a user of the circuit who has a warped disc that was pushing his woofer cone in and out. It was clear to see.

Engage "warp drive", and the woofer stopped moving, but there was absolutely zero audible difference. (and to get a woofer to come out as far as it was, it had significant amplitude).

I never liked the typical "filters" because no matter how well designed, the audio sounded different with and without them engaged, due to the necessary roll-off slope. This thing is transparent. And that's why I'm pursuing it. I believe it to be the best answer to the problem. Most of my records come from thrift stores and trash heaps so, it's necessary for me.

 

[marcok]

It' s not a classic approach , but now I'm beginning to understand .
Thank you
Marco

 

[marcok]

http://waynestegall.com/audio/warpfilter.htm
An other approach , that I think you already know .
A notch filter trimmed for 33 rpm and hipass filter
I 'm becoming younger
Ciao
Marco

 

[J!m]

Interesting. Looks like a very refined filter designnn

 

[borchee]

tracking force with a plastic balance beam and plastic discs of various weights...1.25 grams, exactly.

Made it yourself? I like! And...no, you are not measuring force with it, but comparing masses. It will show the exact same result on the Moon, whereby VTF will be only about 1/6 compared to the Earth, due to Moon's lower gravity. Measuring forces ain't an easy task.

My point is directed towards people claiming decimals at one end and speculating at the other. I don't mind, if somebody is anal about it, in fact I do appreciate it - just be anal the whole way! (buoyancy is only my over-the-top example):

1) VTF...if chasing the second decimal point, you must use some sort of a force gauge, not a weighing scale, or at least take into account the "agreed-upon average" gravitational acceleration on the face of the Earth is 9,81m/s²...the actual you don't know.
Hmmm, WTF seems the more appropriate term.
2) VTA
- do you know the cutting angle of your record(s)? If so, you surely set it for each different one? And why don't you?!
- record thickness...again, individual settings
- thicker/thinner mat...
- VTF/WTF...
4) azimuth...isn't there an expression about mirrors?...and smoke
5) anti-skating...eeehm...what?...where?...when?...why?
6) overhang, tracking angle...
7) matching an arm with a cartridge to get the desired resonant frequency...why is this so difficult?!:
- you know the stylus' compliance
- you know the arm's effective mass
- you know the masses of cartridge, shell, lifter, screws, shims and their effective masses
- you know the effective lenght
- now fill this data (don't forget the compliance conversion if stated at 100Hz) into one of the equations floating around, let it simmer for fifty years...et voilà!...an exact hit-and-miss ballpark aproximation of a checkee in a baskee.
8) and what not...but to start the anal-journey on a solid ground...first of all: Go linear; a radial arm is flawed by its nature!

Let common sense prevail, pretty please with sugar on top:

- weighin scale is fine...no need for a really expensive one
- set VTF according to manufacterer
- get a test record, if you fancy some setting-tweeking, or wanting to verify the stylus and/or cantilever are mounted within specs
- keep the records and stylus clean!
- if you just want to taste vinyl for the first time...get a new plug-and-play (cartridge mounted and pre-set) turntable.

Lean back and enjoy the music!!!...scrapped out of vinyl grooves with a stone - - I'll wear my precious records out by playing them...yada yada.

May the Hearing be with you!
Borut

Edit: BB, I see now you didn't make it yourself. Still like it.

 

[Makymak]

Specs.... Well, it's something very mysterious. To chace that last 0.01db... no, thanks. For me, sounds good? It's good... As one person I really respect (and I think he's here) said once, sound quality can't always pass on the paper. Maths is good, physics is good but likes and taste don't have to follow physical lows. But I'm just an amateur so I may miss something here.

@borchee your example of buoyancy was a very good example of extreme thinking. For me, it was a very good game of mind. A riddle. Oops, did I said game? Yes! It was something that relaxed me and I truly enjoyed it, as I enjoy listening to a good record or reading a good book. And I thank you for that. But, personally, I don't feel I have to finish MIT to listen to a record; my life is quite short... And maybe that's why I will always be an amateur. I'm ok with that! And for God's sake, I don't judge people who are thinking that way, who am I to judge. I too appreciate it! What I'm saying is, all that is just not for me.

 

[borchee]

I don't feel I have to finish MIT to listen to a record

Exactly, nobody should!

I never discuss sound quality, because it's subjective at the end. Heck, my perception is not constant even throughout a regular day, not to mention different states of mind or heart...or belly. There's nothing I can do about it. And as a side note...the unstable medium, sound waves relly upon to travel, doesn't help consistency much as well.

If it sounds good to one, what is there to object?!

On the other hand, I do differentiate between good (the one I like) sound and High Fidelity of reproduction/reading information. As this is done by phisycal contact stylus/groove, there is a best setting for a given stylus shape (and cantilever/suspension compliance). Is this worth chasing?...sure, why not...to a reasonable extent, but I don't see it as a must-do.

Choosing a cartridge a tonearm will harmonize with - or better said, not fight with - is the tricky part, in my opinnion. How the hell can one find the propper one with lack of information while drawning in the ocean of misinformation. Terms like heavy/light tonearm and low/high compliance ain't revelations either.

Oh well, I only have a Revox B790...with his mini-mass-lenght-tonearm, the possibility to adjust shit, except VTF, and flipping the bloody thing upside down to change the cartridge. Love it!

Borut

 

[J!m]

Your “ideal” alignment of stylus and groove is reflected in rocket nozzle design.

Perfect DeLaval nozzle design is only perfect under one set of conditions- where the ratio of throat pressure and exit pressure are in harmony. And since the nozzle is a fixed shape, you have to make assumptions based on measurements for the nozzle exit pressure.

So pressure of exit as sea level is much different than at 10,000 feet. You have to design based on exactly what pressure you want it to be most efficient at.

Staged rockets make best use of this, because each stage can be optimized for their target pressure (altitude). Smart.

 

[Makymak]

I don't disagree, at all with both Borut and Jim. I just see it from a different perspective. To my eyes (and ears and... belly, why not?!!!) it seems that chasing perfection in hi-fi reproduction is like hunting witches. Every step on the reproduction path has tolerances and sometimes difficult to predict or estimate. The wear of the parts make it more complex. When listen to music I want to enjoy the moment so I choose to leave aside any anxiety if I done it the right way so I can enjoy the last drop of it. For me, what matters most is my equipment to be in perfect working order and this thread proved it wasn't. Of course my setup isn't optimum for reasons that are elementary knowledge but that doesn't prevent me from enjoying it!

 

[J!m]

One reason why I’m always tightening tolerance when I repair something. Keeps parts closer to the original design “ideal” value, and (in theory) would take longer to drift from it.

I don’t get too caught up in which animal fur felt is used in a capacitor, and which mine the silver came from.

In general, you get what you pay for. But more expensive does not guarantee better quality or better”fitment for purpose”.

 

[borchee]

only perfect under one set of conditions

Yes, I know everything about rocket nozzles - I saw October Sky.
But seriously...I'm actually talking about taking certain things not to seriously (knowing when to stop) - of course, I won't blow my ass up by setting the VTF wrong.

I'm full of secret knowledge - I even know how to win the lottery, and it's easier than chasing null-points.

 

[8991XJ]

Made it yourself? I like!

That is actually the original stylus force balance that came with the Acoustic Research turntable. My brother got one on about 1970. Came with a nice set of different masses to allow proper tonearm setup on planet earth. It was not taken to the moon for proper setup there because the correct force would not be set properly in that low gravitational environment.

 

[borchee]

I did edit the post regarding my question about DIY, but thanks for the info about it being an original.

It can be used on the Moon with equal precission, just stack 7,5g of them balancing masses up. The tonearm's counterweight may present a problem though. Possibly it can't be set close enough to the pivot, so its mass has to be shaved off....altering effective mass/resonant frequency.